To remove excess starch from the potatoes, put the slices in a large bowl and fill with cold water.,Stir the potatoes with your hand and pour out the cloudy water, as if you are rinsing rice.,Repeat until the water is clear.,Add enough water to cover the potatoes by 1 inch.,Add a tray of ice cubes and refrigerate for at least 30 minutes or for up to several hours.,The colder the potatoes are, the better their interiors will fry.,Line a baking sheet with a triple layer of paper towels and place next to the stove.,Pour oil to a depth of 1 1/2 inches into a 5-quart Dutch oven and heat over medium heat to 325F on a deep-frying thermometer.,(If you dont have a thermometer, stand a dry bamboo chopstick in the oil; if small bubbles gather on the surface around the chopstick in a few seconds, the oil is ready.),While the oil heats, drain the potatoes, discarding any unmelted ice cubes.,Blot the potatoes thoroughly dry with paper towels or lint-free dish towels.,Set the potatoes near the stove.,In a bowl, combine the marinade and beef and mix well with chopsticks or your fingers.,Set aside to marinate while you fry the potatoes.,When the oil is ready, increase the heat to medium-high.,(The cold potatoes will cause the oil temperature to drop dramatically.),Carefully add the potatoes to the oil, which will suddenly boil and sound like falling rain.,As the potatoes fry, use a skimmer or spoon to stir them gently in the oil.,When they start to turn gold, after about 8 minutes, use the skimmer to transfer them to the baking sheet, spreading them out to drain.,Let them cool for at least 10 minutes before refrying.,(You may let them sit for up to 3 hours, in which case you must cover and refrigerate the marinating beef and then return it to room temperature before stir-frying.),For the second frying, reheat the oil over medium-high heat to 350F.,Pick up the potatoes by the triple layer of paper towels and use your hand to scoot them off into the oil.,______,Meanwhile, line the baking sheet with new paper towels.,Using the skimmer, transfer the finished potatoes to the paper-lined baking sheet, spreading them out to drain.,Lightly salt the potatoes while they are hot and transfer to a platter.,In a wok or large skillet, heat the 1 tablespoon oil over medium-high heat until hot but not smoking.,Add the onion and stir-fry for about 30 seconds, or until fragrant.,Add the garlic and stir-fry for about 15 seconds, or until aromatic.,To prevent the onion and garlic from getting stuck under the beef and charring, bank them on one side of the pan.,Increase the heat to high and add the beef, spreading it out into a single layer.,Let it cook, undisturbed, for about 1 minute.,When the beef begins to brown, use a spatula to flip and stir-fry it, incorporating the onion and garlic, for another 2 to 3 minutes, or until the beef no longer looks rare and is done.,Transfer the beef, onion, and garlic to the platter holding the potatoes, centering it on top of the potatoes and leaving a golden rim for an attractive presentation.,Sprinkle with pepper and garnish with the cilantro.,Serve immediately.